Ferroelectric Triglycine Sulfate Research Articles

Investigations on theoretical models describing the load-indentation size dependence for (001), (010), (101), (1̄1̄1) and (1̄11) faces of triglycine sulphate

Ferroelectric triglycine sulphate (TGS) single crystals were grown by slow evaporation technique over a period of 30–40 days. The Vickers microhardness studies have been carried out on (001), (010), (101), ([Formula: see text][Formula: see text]1) and ([Formula: see text]11) faces of the TGS crystal. The as-grown (001) face and (010) face with the ferroelectric phase were used to study the temperature dependence of hardness. The indentation size effect (ISE) described using the five theoretical models viz., Meyer’s law, Hays–Kendall, elastic/plastic deformation (EPD), proportional specimen resistance (PSR) and modified PSR model has been investigated on all the crystal faces under study. The experimental results show that the modified PSR model is more accurate at generating load-independent hardness data and also for explaining the origin of ISE.

Piezoelectric and Pyroelectric Properties of Organic MDABCO-NH4Cl3 Perovskite for Flexible Energy Harvesting

This study describes the synthesis and characterization of the lead-free organic ferroelectric perovskite N-methyl-N’-diazabicyclo [2.2.2]octonium)-ammonium trichloride (MDABCO-NH4Cl3). The electrospinning technique was employed to obtain nanofibers embedded with this perovskite in a PVC polymer for hybrid fiber production. The dielectric, piezoelectric, and pyroelectric properties of these fibers were carefully examined. Based on measurements of the dielectric permittivity temperature and frequency dependence, together with the pyroelectric results, a transition from a high temperature paraelectric to a ferroelectric phase that persisted at room temperature was found to occur at 438 K. The measured pyroelectric coefficient yielded values as high as 290 μC K−1 m−2, which is in between the values reported for MDABCO-NH4I3 and the semiorganic ferroelectric triglycine sulfate (TGS). The hybrid nanofibers exhibited good morphological characteristics and demonstrated very good piezoelectric properties. Specifically, a piezoelectric coefficient of 42 pC/N was obtained when applying a periodical force of 3 N and a piezoelectric voltage coefficient of geff = 0.65 V mN−1. The performance of these fibers is on par with that of materials discussed in the existing literature for the fabrication of nano energy-harvesting generators. Importantly, the perovskite nanocrystals within the fibers are protected from degradation by the surrounding polymer, making them a promising environmentally friendly platform for flexible mechanical energy harvesting.

Dielectric and Magnetoelectric Properties of TGS-Magnetite Composite.

In our studies, we combined two powdered materials, i.e., ferroelectric triglycine sulfate (TGS) and ferrimagnetic magnetite Fe3O4, to obtain a magnetoelectric composite. The ferroelectric (E) part, i.e., TGS, was a hybrid organic-inorganic crystal, which we obtained as a pure single crystal from an aqueous solution using a static water evaporation method. The magnetic (M) part of the composite was commercially available magnetite. The samples used for the dielectric and magnetoelectric measurements were cold-pressed and made in the form of a circular tablet. The measuring electrodes were made of silver-based conductive paste and were attached to the sample. We measured the temperature dependencies of selected electrical parameters (e.g., dielectric permittivity, electrical capacity, and loss angle tangent). We used the dynamic lock-in method to check whether magnetoelectric coupling existed between the E and M phases. In this paper, we present the dielectric properties of pure monocrystalline TGS as a reference sample and compare the results for TGS powder, TGS + carbon powder, and TGS + Fe3O4 powder. The magnetoelectric coupling presumably appeared for the composite TGS + 10 wt. % Fe3O4, as evidenced by the shift in the phase transition temperature in the TGS. Moreover, the theoretical interpretation of the effect is proposed.

Effect of adding technologically processed antibodies to interferon-gamma into a parent solution on the structural features of triglycine sulfate crystals grown from this solution

Objectives. Ferroelectric triglycine sulfate (TGS) belongs to a group of crystals whose properties are sensitive even to minor changes in growth conditions. The mechanism of spontaneous polarization in TGS is associated with the adjustment of protons which participate in the formation of hydrogen bonds. Therefore, the state of the parent solution plays an important role in the crystal formation. The study aims to investigate the structural features of TGS crystals grown using aqueous alcoholic solutions of technologically processed antibodies to interferon-gamma, in comparison with those of the crystals grown using the control solutions (technologically processed phosphate-buffered saline and intact aqueous alcoholic solution).Methods. X-ray diffraction assay and Raman spectroscopy.Results. The effect of solutions of the technologically processed antibodies to interferongamma added to a parent solution on the growth of TGS single crystals is established. This effect manifests in the changing in occupancy of the proton sublattice of the crystal grown from the parent solution containing technologically processed antibodies to interferon-gamma, as compared with the crystals grown from the control solutions. In the case of the crystal grown from the solution containing technologically processed antibodies to interferon-gamma, this change in the occupancy of the proton lattice is expressed in an increase in the length of N2–C3 bonds.Conclusions. Adding the technologically processed antibodies in the parent solution before the crystal growth can affect the structure of TGS crystals.

Acoustic shock wave-induced ordered to disordered switchable phase transitions: A case study of ferroelectric triglycine sulphate single crystal for the application of molecular switches

Highly efficient switchable materials for external stimuli have impressive applications in the development of precious sensor devices. However, most of the materials do not possess effective switchable structural features such that finding potential switchable materials is one of the critical research tasks for materials science researchers. In the present research perspective, we demonstrate successive switchable phase transitions occurring between the order to disorder states in the ferroelectric triglycine sulphate (TGS) single crystal along the (011) plane with respect to the number of shock pulses (0,1 and 2 counts) and the observed results are evaluated by the diffraction, spectroscopic, microscopic and thermal approaches. The observed switchable phase transitions occur due to the shock wave-induced inter-conversion of planar configuration to the non-planar configuration of Glycine molecules, particularly GII and GIII. The ratio of the normalized Raman bands Sym-CH2/Asym-CH2 is found to be 2.0 and 2.5 for the respective order to disorder states such that these values are identified to be well-matched with the literature reports. In addition to that, the SEM images authenticate that, during the amorphous to crystalline phase transitions, the appearance of well-defined (011) plane on the surface is ensured due to the dynamic recrystallization. To the best of our knowledge, to date, it is probably the first report for the phase switching of order to disorder states of TGS sample by the impact of acoustical shock waves and because of its efficient switchability, it can be strongly suggested for the application of molecular switches.

Magnetically Induced Effects in Ferroelectric Triglycine Sulfate Crystals with Chromium Impurity

Magnetically Induced Effects in Ferroelectric Triglycine Sulfate Crystals with Chromium Impurity

Magnetically Induced Effects in Ferroelectric Triglycine Sulfate Crystals with Chromium Impurity

The influence of a permanent magnetic field on macro- and nanoscopic properties of triglycine sulfate (TGS) crystals with impurity chromium (TGS-Cr) has been investigated. This work continues the previous studies of magnetically induced effects in ferroelectrics. A specific feature of TGS crystals is the presence of a nanoscale relief on a polar (010) cleavage; this nanorelief is a qualitative characteristic of the crystal defect structure. It is shown that the exposure of a crystal in a magnetic field of 2 T leads to a change in its dielectric properties, accompanied by a long-term transformation of the nanorelief. The results obtained are indicative of a magnetically induced change in the defect crystal structure. A qualitative difference is found between the magnetically induced effects in TGS-Cr crystals and undoped TGS crystals. The relationship between the magnetically induced effects and structural defects is discussed.

Ferroelectric properties of triglycine sulfate crystals doped with glycine analogs

Single crystals of ferroelectric triglycine sulfate doped with glycine analogs serine, threonine, lactic acid, and alaninol were grown via the slow solvent evaporation method. The resulting ferroelectric domain structures and polarization–electric field hysteresis loops revealed that these dopants caused triglycine sulfate to form a multidomain structure. This was attributed to hydrogen bonds not being formed, which is significant in polarization reversal, due to the side chains and the substituents of the dopant molecules. Therefore, the dopants did not affect the surrounding dipoles enough to cause cooperative phenomena, such as dipole‒dipole interactions, and do not result in the formation of a single- domain, unlike alanine in our previous study.

Terahertz wave rectification in a ferroelectric triglycine sulfate single crystal.

The effect of optical rectification (OR) in the terahertz range (THz rectification, TR) is experimentally demonstrated. The effect consists of generating a DC voltage on the faces of a ferroelectric triglycine sulfate (TGS) single crystal under the action of pulsed radiation with a frequency of 1.57 and 1.96 THz and an electric field strength per pulse of 1.3 and 1.5 MV/m, respectively. The FLARE FELIX free-electron laser system (Radboud University, The Netherlands) was used as a THz radiation source. The TR effect makes it possible to directly determine the nonlinear susceptibilities of media (including those under conditions of strong absorption) without any reference or optical channel calibration and also without the need of Fourier transform.

A Polymorph of Dipeptide Halide Glycyl-L-Alanine Hydroiodide Monohydrate: Crystal Structure, Optical Second Harmonic Generation, Piezoelectricity and Pyroelectricity.

A polymorph of glycyl-L-alanine HI.H2O is synthesized from chiral cyclo-glycyl-L-alanine dipeptide. The dipeptide is known to show molecular flexibility in different environments, which leads to polymorphism. The crystal structure of the glycyl-L-alanine HI.H2O polymorph is determined at room temperature and indicates that the space group is polar (P21), with two molecules per unit cell and unit cell parameters a = 7.747 Å, b = 6.435 Å, c = 10.941 Å, α = 90°, β = 107.53(3)°, γ = 90° and V = 520.1(7) Å3. Crystallization in the polar point group 2, with one polar axis parallel to the b axis, allows pyroelectricity and optical second harmonic generation. Thermal melting of the glycyl-L-alanine HI.H2O polymorph starts at 533 K, close to the melting temperature reported for cyclo-glycyl-L-alanine (531 K) and 32 K lower than that reported for linear glycyl-L-alanine dipeptide (563 K), suggesting that although the dipeptide, when crystallized in the polymorphic form, is not anymore in its cyclic form, it keeps a memory of its initial closed chain and therefore shows a thermal memory effect. Here, we report a pyroelectric coefficient as high as 45 µC/m2K occurring at 345 K, one order of magnitude smaller than that of semi-organic ferroelectric triglycine sulphate (TGS) crystal. Moreover, the glycyl-L-alanine HI.H2O polymorph displays a nonlinear optical effective coefficient of 0.14 pm/V, around 14 times smaller than the value from a phase-matched inorganic barium borate (BBO) single crystal. The new polymorph displays an effective piezoelectric coefficient equal to deff=280 pCN-1, when embedded into electrospun polymer fibers, indicating its suitability as an active system for energy harvesting.

In situ X-ray diffraction studies of deformation behavior of ferroelectric triglycine sulfate under uniaxial compression

A combination of high-resolution X-ray diffraction and X-ray diffraction topography was used for analysis and visualization of elastic strain in ferroelectric triglycine sulfate (TGS) single crystals under uniaxial compression. Diffraction peaks and topographs were obtained for both the 400 and 060 reflections of TGS in transmission geometry under gradually increased compression stress up to 3.5 MPa applied along the [100] and [010] crystallographic directions. All the diffraction data from the sample were obtained from the whole crystal volume with wide beam illumination. Analysis of diffraction patterns revealed a nonlinear increase in integral intensity versus stress and a linear increase in peak broadening versus stress for all compression measurement combinations. The topographs confirmed that the formation of uniform and non-uniform strain fields depended on the direction of crystal compression and its relationship with integral intensity. A twinning process was found for the in-plane reflection along the [100] direction. All the effects induced by compression were reversible after decompression of the sample. According to the results, a significant anisotropy of deformation processes depending on the crystallographic direction was observed, which can be explained by the proposed deformation mechanism with superposition of compression stress, the piezoelectric effect and ferroelectric domain evolution.

Dielectric magnetochiral anisotropy in triglycine sulfate

Recently, we have predicted, solely on the basis of symmetry arguments, the existence of strong magnetochiral anisotropy in the displacement current in chiral dielectrics and reported its experimental observation in chiral ferroelectrics near their ferroelectric-paraelectric phase transitions [Nat. Commun. 13, 3564 (2022).]. Here, we present a microscopic model that describes both direct and inverse dielectric magnetochiral anisotropy (dMChA) in the chiral ferroelectric triglycine sulfate (TGS), based on the specifics of the charge movement in a time-varying electric field. We predict a strong inverse dMChA in TGS that should be within reach of experimental observation and we find good agreement between our model and the experimental observation of the direct dMChA in TGS.

Lead-Free MDABCO-NH4I3 Perovskite Crystals Embedded in Electrospun Nanofibers.

In this work, we introduce lead-free organic ferroelectric perovskite N-methyl-N'-diazabicyclo[2.2.2]octonium)-ammonium triiodide (MDABCO-NH4I3) nanocrystals embedded in three different polymer fibers fabricated by the electrospinning technique, as mechanical energy harvesters. Molecular ferroelectrics offer the advantage of structural diversity and tunability, easy fabrication, and mechanical flexibility. Organic-inorganic hybrid materials are new low-symmetry emerging materials that may be used as energy harvesters because of their piezoelectric or ferroelectric properties. Among these, ferroelectric metal-free perovskites are a class of recently discovered multifunctional materials. The doped nanofibers, which are very flexible and have a high Young modulus, behave as active piezoelectric energy harvesting sources that produce a piezoelectric voltage coefficient up to geff = 3.6 VmN-1 and show a blue intense luminescence band at 325 nm. In this work, the pyroelectric coefficient is reported for the MDABCO-NH4I3 perovskite inserted in electrospun fibers. At the ferroelectric-paraelectric phase transition, the embedded nanocrystals display a pyroelectric coefficient as high as 194 × 10-6 Cm-2k-1, within the same order of magnitude as that reported for the state-of-the-art bulk ferroelectric triglycine sulfate (TGS). The perovskite nanocrystals embedded into the polymer fibers remain stable in their piezoelectric output response, and no degradation is caused by oxidation, making the piezoelectric perovskite nanofibers suitable to be used as flexible energy harvesters.

Voltage controlled awakening of memristor-like dynamic current–voltage loops of ferroelectric triglycine sulfate

For the study of polarization reversal features in the structure of "mixed ionic-electronic conductor - on - ferroelectric" type, the hydrogen bonded molecular ferroelectric crystal triglycine sulphate (TGS) is used. The dynamic currant-voltage (I-V-) loops of thin TGS plates of polar (010) cut with dissimilar electrodes on the opposite surfaces (vacuum deposited Ag and Ag-paste diluted with a water-ethanol mixture) are investigated. After electroforming in the low-voltage vicinity of coercive voltage, during further cycling, a reversible transformation of I-V-loop shape occurs from typical of non-linear dielectrics to typical of memristive systems and than to typical of ferroelectrics (and vice versa) with a sequential increase (decrease) of drawing voltage amplitude. Such "awakening" and "falling asleep" of I-V-loops of the memristor type is apparently associated with reversible electromigration and accumulation of charged species (e.g., protons), in the hydrated surface layer of TGS as a component of electrochemical capacitor-on-ferroelectric structure. The observed transformation can be explained by considering the coupled ion transfer and polarization reversal taking into account the swinging of the boundary of the built-in chemical inhomogeneity under conditions of linear and/or nonlinear dynamics of ion drift and ionic concentration polarization caused by charged species transfer under the applied voltage.

Influence of nickel (Ni7+) Swift Heavy Ion (SHI) irradiation on the optical, topological, dielectric, piezoelectric and ferroelectric properties of 〈0 1 1〉 oriented ferroelectric triglycine sulphate single crystals

Nickel (Ni7+) Swift Heavy Ion (SHI) irradiation effects on the optical, topological, dielectric, piezo- electric and ferroelectric properties of 〈011〉 oriented ferroelectric Triglycine sulphate (TGS) single crystals have been investigated. Dielectric constant found to have increased more than 9 fold upon irradiation. A marginal shift in Tc (325–332 K) has been noted upon irradiation. A significant improvement in the piezoelectric coefficient has been observed for irradiated samples when compared to the 〈011〉 pristine TGS. Ferroelectric studies reveal the decrease in coercive field due to the irradiation with Ni7+ ions. The results obtained from all studies have been discussed in detail.

Asymmetric autocatalysis triggered by triglycine sulfate with switchable chirality by altering the direction of the applied electric field.

Triglycine sulfate (TGS) acts as a chiral trigger for asymmetric autocatalysis with amplification of enantiomeric excess, i.e., the Soai reaction. Therefore, molecular chirality of highly enantioenriched organic compounds is controlled by a ferroelectric crystal TGS, whose polarization is altered by an electric field.

Dielectric Spectra of TGS + Сr Crystals in the Vicinity of Phase Transition

Dependencies of the complex permittivity of chromium-doped ferroelectric triglycine sulfate crystals (TGS + Cr) have been measured using dielectric spectroscopy method in a frequency range of 1–107 Hz and a temperature range of 23–60°C upon heating and cooling. The dielectric spectra are analyzed by considering the temperature‒frequency dependences of the real (e') and imaginary (e") parts of permittivity in the immediate vicinity of the phase transition using the dynamic conductance model and taking into account resonance processes. Good agreement between calculated and experimental data is obtained for the dielectric response of TGS + Cr crystal near the Curie temperature.

Surface and bulk modifications in gamma irradiated [formula omitted]011[formula omitted] oriented ferroelectric triglycine sulphate (tgs) single crystals

Bulk and transparent single crystals of ferroelectric Triglycine sulphate (TGS) have been grown along 〈011〉 crystallographic orientation. The grown crystals with prominent 〈011〉 plane were cut into uniform dimensions and lapped with reasonable quality of surface polishing. Platelets of 〈011〉 cut TGS were subjected to gamma irradiation with a dosage of 10–50 kGy using Cobalt-60 (60Co) as the source of radiation. 〈011〉 faceted TGS crystal turns to pale yellow colour due to irradiation induced defects and has produced free radical ions. The irradiation induced modification of spectral properties like UV–vis–NIR, Raman and Electron Paramagnetic Resonance (EPR) measurements have been recorded for the specimens of TGS. Dielectric, Ferroelectric and Piezo force microscopy studies of as grown single crystal were also carried out and there results have been discussed in detail.

TGS crystal growth below and above Curie temperature (Tc)

Ferroelectric triglycine sulphate (TGS) single crystals were grown by conventional slow cooling and unidirectional solution growth method below and above its Curie temperature (Tc). The evolution of morphology of TGS crystals during conventional growth method was imaged in an online and in-situ manner using laser shadowgraphy, and the growth rates of the crystals along a, b and c-axis were measured in both the temperature regimes. It was found that the growth rates of crystal grown above Tc was higher than that of the crystal grown below Tc. TGS crystals oriented along [010] polar direction and having large (010) habit face were successfully grown below and above its Curie temperature (Tc) by Sankaranarayanan-Ramasamy (SR) unidirectional solution growth method. Time-lapsed photographs of SR growth process were captured at regular interval of time, from where the growth rates of crystals along [010] direction was computed to be 1.5 and 2.2 mm/day for crystals grown below and above Tc respectively. The growth conditions were optimized and the dimension of the grown crystals were 60 mm length and 15 mm diameter for below Tc and 35 mm length and 15 mm diameter for above Tc. Using shadowgraphy, the buoyancy-driven convective patterns around the growing TGS crystals were imaged and the gradual buildup of this activity with the dimension of the crystal and time of the growth was investigated. Shadowgraphy was also used to map the evolution of morphology of TGS crystals growing below and above Tc, and growth rates along the three main crystallographic directions were computed. Mach-Zehnder interferometry was used to image development of concentration gradient in the crystallizer during growth.

Influence of external electric field on phase transitions in the thin film ferroelectrics

Based on the phenomenological theory of Landau–Ginzburg–Devonshire, the singularities of the phase transition in a thin ferroelectric film in external electric field are investigated depending on the film thickness and the type of polarization fixed on its planes. It was found that in electric field the phase transition shifts in temperature, and the shift value depends on the film thickness and the properties of its planes. In the linear approximation at the weak fields, the temperature shift of phase transition does not depend on the field strength until a certain definite value. For ferroelectric triglycine sulfate film with the thickness 35 nm, this value is 116 V/cm.